The invention relates to a method for biometric identification or authentication of persons. The invention furthermore relates to a system for performing said method.
It is known that biometric comparisons can be used both for identifying and authenticating persons. When used for identification, the identification occurs without prior knowledge (1:n comparison), wherein the characteristics of a person, having been detected biometrically using a suitable method and/or system, are compared to data sets of a plurality of previously detected persons for the purposes of establishing identity. For this, data sets for the person are stored in particular centrally in the biometric system. In the case of authentication, a selection is examined (1:1 comparison), the biometrically detected characteristics of a person being compared to the characteristics of a previously detected person to determine if there is a match. The data set to be compared can be stored centrally in the biometric system or there is also the option of storing the data set on a medium, such as e.g. a chip card, the person to be authenticated providing the aforesaid medium to the system. In the case of both identification and authentication, the biometric characteristics are calculated by computer from the detected image data. A fundamental problem of biometric methods is that an image of the biometric object, such as fingertip, face, or iris, might not be differentiable from reproductions or copies of the objects, and thus the biometric system can be deceived and the certainty of the identification or authentication cannot be assured. Thus in current biometric methods such as fingerprinting, face, iris, or speech, the biometric object is “freely” accessible. Since fingerprints are left everywhere, it is easy for fingerprint systems to be deceived using copies. Iris scanner systems can also be overcome relatively easily, for instance using specially prepared and/or created contact lenses or simply using photographs of the iris with the correct proportions. It is relatively simple to create suitable copies of a biometrically measured object to be identified. It is a major problem for such biometric systems that as a rule it is not possible to decide whether the object presented for identification or authentication is an original body part or only a reproduction thereof. Moreover, any available biodetection such as for instance thermal, capacitive, or the like can be overcome using relatively simple technical means. The quality of biometric methods and/or systems for identification that use pattern detection algorithms is normally indicated using two parameters, specifically the false rejection rate (FRR) and the false acceptance rate (FAR). The FRR provides the percentage of persons or individuals incorrectly rejected by the system, wherein the two data sets of biometric characteristics that are to be compared originate from the same individual but the system does not make a match. Ideally this figure is 0%. The FAR provides the percentage of persons incorrectly authenticated by the system, wherein the two data sets of biometric characteristics that are to be compared do not originate from the same individual but are still evaluated as a match by the system. This figure is also ideally 0%.
Known from EP 0 498 280 B1, wherein the applicant is the present assignee, is a device for scanning an object with a ray beam in two largely orthogonal directions. This is a diagnostic laser scanning system by means of which a continuous copy of the retina can be made with different wavelengths. The device contains a first scanner and a second scanner, each having a mirror, the axes of rotation of which run in mutually orthogonal planes. The mirror of the first scanner is disposed a prespecified distance from its axis of rotation. The center point of the mirror of the second scanner is arranged in the center of the aforesaid distance between the axis of rotation and the mirror of the first scanner, the ray beam running from the mirror of the first scanner directly to the mirror of the second scanner. An additional optical system is in the beam path between the aforesaid mirrors. This laser scanning system, which is also called a retina scanner, makes it possible to scan the retina with different wavelengths continuously, specifically without mydriasis or dilation of the pupil using medication.